function preload(){
	//preload delle immagini
	for (i=0; i< preload.arguments.length; i++){
		preimg = new Image(50,50);
		preimg.src=preload.arguments[i];
	}
}
function setVisible(idspan,mode){
	if (mode==true){ visibility='visible'; display='block';}
	else {visibility='hidden'; display='none';}
    document.getElementById(idspan).style.visibility=visibility;
    document.getElementById(idspan).style.display=display;
}

function showCredits(){
	if (document.getElementById('credits').style.display=='none')	Effect.Appear('credits');
	else Effect.Fade('credits');
}